Merge pull request #50 from pythonbpf/dep_inv

Use dependency inversion to remove handler delayed import in eval_expr

Author: r41k0u

pythonbpf/expr/__init__.py

@@ -1,4 +1,4 @@
-from .expr_pass import eval_expr, handle_expr, get_operand_value
+from .expr_pass import eval_expr, handle_expr, get_operand_value, CallHandlerRegistry
 from .type_normalization import convert_to_bool, get_base_type_and_depth, deref_to_depth
 
 __all__ = [
@@ -8,4 +8,5 @@
     "get_base_type_and_depth",
     "deref_to_depth",
     "get_operand_value",
+    "CallHandlerRegistry",
 ]

pythonbpf/expr/expr_pass.py

@@ -15,6 +15,28 @@
 logger: Logger = logging.getLogger(__name__)
 
 
+class CallHandlerRegistry:
+    """Registry for handling different types of calls (helpers, etc.)"""
+
+    _handler = None
+
+    @classmethod
+    def set_handler(cls, handler):
+        """Set the handler for unknown calls"""
+        cls._handler = handler
+
+    @classmethod
+    def handle_call(
+        cls, call, module, builder, func, local_sym_tab, map_sym_tab, structs_sym_tab
+    ):
+        """Handle a call using the registered handler"""
+        if cls._handler is None:
+            return None
+        return cls._handler(
+            call, module, builder, func, local_sym_tab, map_sym_tab, structs_sym_tab
+        )
+
+
 def get_operand_value(
     func, module, operand, builder, local_sym_tab, map_sym_tab, structs_sym_tab=None
 ):
@@ -478,51 +500,14 @@ def eval_expr(
                 structs_sym_tab,
             )
 
-        # delayed import to avoid circular dependency
-        from pythonbpf.helper import HelperHandlerRegistry, handle_helper_call
+        result = CallHandlerRegistry.handle_call(
+            expr, module, builder, func, local_sym_tab, map_sym_tab, structs_sym_tab
+        )
+        if result is not None:
+            return result
 
-        if isinstance(expr.func, ast.Name) and HelperHandlerRegistry.has_handler(
-            expr.func.id
-        ):
-            return handle_helper_call(
-                expr,
-                module,
-                builder,
-                func,
-                local_sym_tab,
-                map_sym_tab,
-                structs_sym_tab,
-            )
-        elif isinstance(expr.func, ast.Attribute):
-            logger.info(f"Handling method call: {ast.dump(expr.func)}")
-            if isinstance(expr.func.value, ast.Call) and isinstance(
-                expr.func.value.func, ast.Name
-            ):
-                method_name = expr.func.attr
-                if HelperHandlerRegistry.has_handler(method_name):
-                    return handle_helper_call(
-                        expr,
-                        module,
-                        builder,
-                        func,
-                        local_sym_tab,
-                        map_sym_tab,
-                        structs_sym_tab,
-                    )
-            elif isinstance(expr.func.value, ast.Name):
-                obj_name = expr.func.value.id
-                method_name = expr.func.attr
-                if obj_name in map_sym_tab:
-                    if HelperHandlerRegistry.has_handler(method_name):
-                        return handle_helper_call(
-                            expr,
-                            module,
-                            builder,
-                            func,
-                            local_sym_tab,
-                            map_sym_tab,
-                            structs_sym_tab,
-                        )
+        logger.warning(f"Unknown call: {ast.dump(expr)}")
+        return None
     elif isinstance(expr, ast.Attribute):
         return _handle_attribute_expr(expr, local_sym_tab, structs_sym_tab, builder)
     elif isinstance(expr, ast.BinOp):

pythonbpf/helper/__init__.py

@@ -2,6 +2,58 @@
 from .bpf_helper_handler import handle_helper_call
 from .helpers import ktime, pid, deref, XDP_DROP, XDP_PASS
 
+
+# Register the helper handler with expr module
+def _register_helper_handler():
+    """Register helper call handler with the expression evaluator"""
+    from pythonbpf.expr.expr_pass import CallHandlerRegistry
+
+    def helper_call_handler(
+        call, module, builder, func, local_sym_tab, map_sym_tab, structs_sym_tab
+    ):
+        """Check if call is a helper and handle it"""
+        import ast
+
+        # Check for direct helper calls (e.g., ktime(), print())
+        if isinstance(call.func, ast.Name):
+            if HelperHandlerRegistry.has_handler(call.func.id):
+                return handle_helper_call(
+                    call,
+                    module,
+                    builder,
+                    func,
+                    local_sym_tab,
+                    map_sym_tab,
+                    structs_sym_tab,
+                )
+
+        # Check for method calls (e.g., map.lookup())
+        elif isinstance(call.func, ast.Attribute):
+            method_name = call.func.attr
+
+            # Handle: my_map.lookup(key)
+            if isinstance(call.func.value, ast.Name):
+                obj_name = call.func.value.id
+                if map_sym_tab and obj_name in map_sym_tab:
+                    if HelperHandlerRegistry.has_handler(method_name):
+                        return handle_helper_call(
+                            call,
+                            module,
+                            builder,
+                            func,
+                            local_sym_tab,
+                            map_sym_tab,
+                            structs_sym_tab,
+                        )
+
+        return None
+
+    CallHandlerRegistry.set_handler(helper_call_handler)
+
+
+# Register on module import
+_register_helper_handler()
+
 __all__ = [
     "HelperHandlerRegistry",
     "reset_scratch_pool",